Recently, with the development of freezing technique, frozen noodles, which are prepared by freezing cooked noodles which can have been cooked so as to be edible such as udon or Chinese noodles, have been distributed and commercially available. Such frozen noodles have an advantage in that they can be stored for a long time. Furthermore, frozen cooked noodles, sauce and toppings are packaged in a single package and sold as easy-to-cook frozen foods in the market. However, some cooked noodles become soggy; with the result that the noodles may lose elasticity and have soft texture, and present matte and dull-color appearance. In addition, some noodles stored in a freezer become white, lose smoothness and become firm but brittle and nonelastic in texture; in other words, so-called freezer burn may occur.
A high-pressure extrusion noodle production method where noodle dough is extruded at a high pressure is conventionally known as a process for making Italian pastas such as spaghetti and macaroni (sometimes referred to simply as pasta in the specification). The high-pressure extrusion noodle production method has been generally used for producing dry pasta. More specifically, dry pasta is produced by extruding pasta dough at a high pressure, followed by drying. Patent Literatures 1 to 3 describe production of frozen pasta by boiling raw noodle strands or semidry noodle strands, which are obtained by extrusion molding of pasta dough, followed by freezing. Since pasta is generally produced mainly from hard wheat flour such as durum-semolina and durum wheat flour, the pasta has a characteristic texture, i.e., relatively chewy and firm and crispy texture. Pasta produced by high-pressure extrusion, such as dry pasta further apparently has such a characteristic.
In contrast, noodles such as udon or Chinese noodles are preferred to have appropriate viscosity and elasticity. In order to provide such a texture, in some cases when producing udon or Chinese noodles in the art, ingredients such as wheat flour are strictly selected to make the quality (hard, soft) of starch appropriate, the content of the protein of the flour ingredient is controlled, or additives such as kansui, gluten, starch, egg, albumen powder, salt and gums are used to increase viscosity and elasticity of dough.
For example, Patent Literature 4 describes a method for making frozen noodles by freezing pregelatinized noodles made from wheat flour containing at least 12 wt % of a crude protein, etherified or acetylated tapioca starch and gluten. Patent Literature 5 describes a method for making raw noodles by extruding a mixture of wheat flour, vital gluten and/or egg white and water under reduced pressure. Patent Literature 6 describes a method for making Chinese noodles by adding kansui to a mixture of wheat flour, starch, vital powdery gluten and egg white, kneading the mixture, and then extruding the resultant noodle sheet in a deaeration condition at a low pressure of about 30 kg/cm2 or less and further rolling the sheet to mold into noodle strands. Patent Literature 7 describes a method for making Chinese-style noodles by adding kansui to a powder mixture of durum-semolina and starch, kneading the mixture, followed by subjecting the kneaded mixture to extrusion molding.